如何获得我的当前位置和新位置之间的距离？

Question

我想在几分钟后立刻获得当前位置与新（当前）位置之间的距离。我想要一个计时器，每隔一秒就用新距离更新我的标签。

示例：我站在街道上并与当前位置相距300米。我得到一个新的当前位置和一个标签应该给300米。

我在反对c编程方面不是很有经验。 这是我走到这一步：

#import <CoreLocation/CoreLocation.h> 

@interface NormalSoloViewController() <CLLocationManagerDelegate> 
@property (weak, nonatomic) IBOutlet UILabel *lbDistance; 

@end 

@implementation NormalSoloViewController 
{ 
    CLLocationManager *locationManager; 
    CLLocation *firstLocation; 
} 

- (void)viewDidLoad 
{ 

    [super viewDidLoad]; 

    locationManager =[[CLLocationManager alloc] init]; 
    locationManager.distanceFilter = kCLHeadingFilterNone; 
    [locationManager startUpdatingLocation]; 

    firstLocation = locationManager.location; 
} 

- (void)startTimer 
{ 
    [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(updateDistance:) userInfo:nil repeats:YES]; 
} 

- (void)updateDistance:(NSTimer *)timer 
{ 
    double distance = 0; 
    distance = distance + [self calculateDistance]; 
    self.lbDistance.text = [NSString stringWithFormat:@"%f", distance]; 

} 

- (double) calculateDistance { 

    CLLocation *newFirstLocation = firstLocation; 
    CLLocation *secondLocation = locationManager.location; 
    firstLocation = secondLocation; 

    return [newFirstLocation distanceFromLocation:secondLocation]; 
} 

Answer 1

的代码不会工作，因为locationManager.location不能被称为是这样。 我增加了速度到我的应用程序。它的工作原理，但只有经理发送新的信息。

@implementation ViewController 
    { 
     CLLocationManager *locationManager; 
     double distance; 
     double speed; 
     double extraDistance; 
     NSMutableArray *locations; 
     CLLocation *newLocation2; 
     CLLocation *oldLocation2; 
     CLLocation *newLocationCheck; 
    } 

    - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil 
    { 
     self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]; 
     if (self) { 
     } 
     return self; 
    } 

    - (void)viewDidLoad 
    { 
     [super viewDidLoad]; 
     distance =0; 
     speed =0; 
     locationManager = [[CLLocationManager alloc] init]; 
     locations = [[NSMutableArray alloc] init]; 
     locationManager.delegate = self; 
     locationManager.desiredAccuracy = kCLLocationAccuracyBest; 
     [self startTimer]; 
     [locationManager startUpdatingLocation]; 
    } 

    - (void)didReceiveMemoryWarning 
    { 
     [super didReceiveMemoryWarning]; 
     // Dispose of any resources that can be recreated. 
    } 

    - (void)startTimer 
    { 
     // Timer that repeatedly does something every 2 seconds 
     [NSTimer scheduledTimerWithTimeInterval:2 target:self selector:@selector(updateSpeedDistance:) userInfo:nil repeats:YES]; 
    } 

    - (void)updateSpeedDistance:(NSTimer *)timer 
{ 
    // fetches the old and new location out of the array list 
    oldLocation2 = locations[0]; 
    newLocation2 = locations[1]; 

    // checks if theres a new location 
    if (newLocation2 != newLocationCheck) { 

     // if there is only one following location 
     if (oldLocation2 != newLocation2){ 
      distance = distance + [newLocationCheck distanceFromLocation:newLocation2]; 
      speed = [oldLocation2 distanceFromLocation: newLocation2]/2; 
      newLocationCheck = newLocation2; 
     // if there multiple locations avaible 
     } 
     else { 
      distance = distance + [oldLocation2 distanceFromLocation:newLocation2]; 
      speed = [oldLocation2 distanceFromLocation: newLocation2]/2; 
      newLocationCheck = newLocation2; 
     } 
    } 
    // if there's no new location the speed wil drop 
    else { 
     speed = speed /1.2; 
    } 
    self.lbDistance.text = [NSString stringWithFormat:@"Distance: %1.2f m", distance]; 
    self.lbSpeed.text = [NSString stringWithFormat:@"Speed: %1.2f m/s", speed]; 
} 

    - (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation 
    { 
     NSLog(@"didUpdateToLocation: %@", newLocation); 

     if (newLocation != nil && oldLocation != nil) { 
      [locations removeAllObjects]; 
      [locations addObject:oldLocation]; 
      [locations addObject:newLocation]; 
     } 
     else { 
      [locationManager startUpdatingLocation]; 
     } 
    } 

    @end 

Answer 2

只要你可以打电话

// Call for the First Location Latitude & longitude 
    Place* home = [[Place alloc] init]; 
    home.name = @"Home"; 
    home.latitude = [[appDel.dictionaRY1styLoc valueForKey:@"Dict1lat"] doubleValue]; 
    home.longitude = [[appDel.dictionaRY1styLoc valueForKey:@"Dict1Long"] doubleValue]; 
    CLLocationCoordinate2D coordinate21 = (CLLocationCoordinate2D){ home.latitude, home.longitude}; 
    MKCircle *circle1 = [MKCircle circleWithCenterCoordinate:coordinate21 radius:5000]; 
    [mapViewRoute addOverlay:circle1]; 
    CLLocation * locA = [[CLLocation alloc] initWithLatitude:home.latitude longitude:home.longitude]; 



    // Call for the Second Location Latitude & longitude 
    Place* work = [[Place alloc] init]; 
    work.name = @"work"; 
    work.latitude = [[appDel.dictionary2ndyLoc valueForKey:@"Dict2lat"] doubleValue]; 
    work.longitude = [[appDel.dictionary2ndyLoc valueForKey:@"Dict2Long"] doubleValue]; 
    CLLocationCoordinate2D coordinate22 = (CLLocationCoordinate2D){ work.latitude, work.longitude}; 
    MKCircle *circle2 = [MKCircle circleWithCenterCoordinate:coordinate22 radius:5000]; 
    [mapViewRoute addOverlay:circle2]; 
    CLLocation * locB = [[CLLocation alloc] initWithLatitude:work.latitude longitude:work.longitude]; 
    NSLog(@"%f==%f && %f== %f",home.latitude,home.longitude,work.latitude,work.longitude); 

    CLLocationDistance distanceE = [locB distanceFromLocation:locA]; 
    NSLog(@"distanceE: %2f", distanceE/1000); 
    lblDistanceKm.text = [NSString stringWithFormat:@"%.2f KM",(distanceE/1000)]; 

这里CLLocationDistance通过我们的类名可以找到距离